Conventional work machines can be used in many different applications, including those in the areas of construction, agriculture, landscaping, and mining. To perform these applications, work tools are typically mounted to work machine lift arms or other articulated members, and may connect to one or more of the work machine's hydraulic mechanisms.
A work machine operator may drive the work machine, and control any work tools attached thereto, through the use of various operator interfaces. These operator interfaces may control hydraulic fluid flows and pressures, and may thereby control the operation of the attached work tool during performance of the application. For example, work machines may include one or more hydraulic circuits used in actuating various work tool lift and tilt mechanisms on the work machine. In the case of some work tools, an auxiliary hydraulic circuit may be used to supply hydraulic fluid to the work tool for operating various mechanisms located on the work tool.
The demands placed on the auxiliary hydraulic circuit may vary based on a number of factors including, for example, the type and/or manufacturer of the work tool attachment, and the task it is being used to perform. In addition, each particular work tool may have a range of speeds, pressures, flows, or other operational characteristics within which the tool is designed to operate. Operating the work tool within these ranges or design parameters may improve the performance of the work tool. The various design parameters of a given work tool may be within, but different than, the operational tolerances or maximum allowable speeds, pressures, and flows of the work tool and/or work machine. Thus, to improve the performance of a work machine/work tool system it may be necessary to sense the work tool's operational characteristics as it performs a task and alter the work machine's operation such that the work tool functions within the work tool's design parameters.
Current work machine control systems may alter a work machine's operation based on the maximum operational tolerances of the work tool, instead of altering the operation of the work machine based on the work tool's design parameters. For example, U.S. Patent Application Publication No. US 2003/0051470 A1 (“the '470 publication”) discloses a system for controlling hydraulic work tools. The system includes a work machine, a controller computer, and a work tool attached to the work machine. The work tool includes a storage chip, and may include a sensor that collects continual operational information and transmits it to the controller computer. According to the '470 publication, the storage chip on the work tool transmits a signal to the controller computer indicating the maximum operating fluid pressure and maximum operating fluid velocity of the corresponding work tool. The controller computer considers this information to prevent exceeding these operational tolerances of the work tool when calculating the fluid flow rates and pressures required to accomplish a desired application.
Controlling a work machine based on the operational tolerances or limits of a particular work tool may prevent damage to the work tool, but may not improve the performance of the work machine/work tool system for a given application. For example, these tolerances may be unrelated to, and may be significantly higher than, the fluid flow rates or fluid pressures with which the work tool was designed to operate efficiently. In such a situation, a tolerance-based control strategy may control the work machine to perform up to the operational limits of the work tool before affecting a change in the operation of the work machine. As a result, the work tool may be controlled to perform beyond its design parameters and the overall performance of the work machine may be hindered.
The present disclosure provides a work machine control system that avoids some or all of the aforesaid shortcomings in the prior art.